1. Technical Field
The present invention relates to compounds, compositions, formulations, kits, methods of use, and manufacture of quinoline derivatives, and more particularly to 4-anilinoquinoline derivatives as inhibitors of DNA methylation enzymes, modulators of DNA methylation and therapeutic agents for preventing or treating diseases associated with aberrant DNA methylation such as cancer and hematological malignancy.
2. Description of the Related Art
Methylation at the C-5 position of cytosine residues in 5′-m5CpG-3′ sequences plays a major role in gene expression by the silencing of genes (Smith, A. F. A. Curr. Opin. Genet. Devel., 1999, 9, 657). The major enzyme responsible for the maintenance of these methylation patterns during replication is the DNA methyltransferase DNMT1 (Siedlecki et al., Biochem. Biophys. Res. Comm., 2003, 306, 558). DNA methylation is the cause of a number of inherited disease syndromes, and can also have a major role in the development of human cancer. It is the most frequent molecular change in hematopoietic neoplasms (Egger et al., Nature, 2004, 429, 457), and is likely involved in other tumor types; for example, a percentage of patients with sporadic colorectal cancers show methylation and silencing of the gene encoding MLH1 (Kane et al., Cancer Res., 1997, 57, 808).
The most widely-explored inhibitors of DNMT1 are suicide inhibitors such as azacitidine (Vidaza®) and decitabine (Dacogen®), antimetabolites that incorporate into DNA in place of cytosine, and irreversibly trap the enzyme (Egger et al., Nature, 2004, 429, 457; Zhou et al., J. Mol. Biol., 2002, 321, 599). Both compounds are now used clinically for the treatment of myelodysplastic syndromes and lymphoproliferative diseases, but do possess considerable toxicity (Leone et al., Clin. Immunol., 2003, 109, 89). Presumably this is due to incorporation of 5-azacytidine into the DNA. Incorporation of decitabine into the DNA strand has a hypomethylation effect. Each class of differentiated cells has its own distinct methylation pattern. After chromosomal duplication, in order to conserve this pattern of methylation, the 5-methylcytosine on the parental strand serves to direct methylation on the complementary daughter DNA strand. Substituting the carbon at the 5 position of the cytosine for a nitrogen interferes with this normal process of DNA methylation. The replacement of 5-methylcytosine with decitabine at a specific site of methylation produces an irreversible inactivation of DNA methyltransferase, presumably due to formation of a covalent bond between the enzyme and decitabine (Juttermann et al., Proc. Natl. Acad. Sci. USA, 1994, 91, 11797). By specifically inhibiting DNMT1, the enzyme required for maintenance methylation, the aberrant methylation of the tumor suppressor genes can be prevented.
Only a few other small-molecule inhibitors of DNA methylation have been described, including the psammaplin sponge metabolites (Piña et al., J. Org. Chem., 2003, 68, 3866), which are potent direct inhibitors of DNA methyltransferases but are less effective in cellular assays (Godert et al., Bioorg. Med. Chem. Lett., 2006, 16, 3330). Other non-nucleoside demethylating agents such as (−)-epigallocatechin-3-gallate, hydralazine, and procainamide were also shown to be far less effective in reactivating genes than decitabine (Chuang et al., Mol. Cancer Ther., 2005, 4, 1515).
Thus, there still exists a need to develop effective modulators of DNA methylation which can be used in the prevention or treatment of diseases associated with aberrant DNA methylation such as cancer and hematological malignancy.